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A263729 Primes p where (p - 1)/k - 1 is not prime for any integer k >= 1. 3
2, 3, 11, 23, 47, 59, 83, 107, 131, 167, 179, 227, 251, 263, 347, 359, 383, 431, 443, 467, 479, 503, 563, 587, 599, 719, 839, 863, 887, 947, 983, 1019, 1031, 1091, 1187, 1223, 1283, 1307, 1319, 1367, 1439, 1451, 1487 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Primes p such that (p^2 + p*q)/(p + 1) is not integer for all primes q.

Primes p such that d1 - 1, d2 - 1, .. are not primes where d1, d2, .. are all divisors of p - 1.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

EXAMPLE

11 is in this sequence because (11 - 1)/1 - 1 = 9, (11 - 1)/2 - 1 = 4, (11 - 1)/5 - 1 = 1, (11 - 1)/10 - 1 = 0 are nonprimes and 11 is prime.

PROG

(PARI) lista(nn) = {forprime (p=2, nn, ok = 1; for (k=1, p-1, x = (p-1)/k - 1; if (denominator(x)==1 && isprime(x), ok = 0; break); ); if (ok, print1(p, ", ")); ); } \\ Michel Marcus, Nov 02 2015

CROSSREFS

Cf. A027750, A263730, A263770.

Sequence in context: A091310 A040994 A141123 * A246496 A119641 A252005

Adjacent sequences:  A263726 A263727 A263728 * A263730 A263731 A263732

KEYWORD

nonn,easy

AUTHOR

Juri-Stepan Gerasimov, Oct 24 2015

EXTENSIONS

Name edited by Franklin T. Adams-Watters, Oct 31 2015

STATUS

approved

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Last modified August 11 15:12 EDT 2020. Contains 336428 sequences. (Running on oeis4.)